I second Dan310's two suggestions, along with Pretty in Pink, Dirty Dancing, Sixteen Candles, High School Musical, The Princess Diaries, Romeo + Juliet, A Walk to Remember...
Basically, I just used IMDb.com's "Keyword" search function, typed in "teen romance," and up came about 287 titles tagged as "teen romances."
Not saying all the above have solid storyforms, of course; they were just popular in their day...
Hope that helps, and am very intrigued by the idea of you writing a teen romance, MWolleager! Can I see?